Fermi Observationsof TeV Gamma-ray Sources
Hiroyasu Tajima
on behalf of Fermi LAT and GBM Collaborations
KIPAC
SLAC National Accelerator Laboratory(Stanford Linear Accelerator Center)
Stanford University

January 9, 2010
CTA Japan Workshop
ICRR, Japan

Outline✤ Introduction❖ The first year LAT catalog✤ Active Galactic Nuclei (AGN)✤ Supernova remnants (SNR)✤ Gamma-ray bursts (GRB)✤ Extragalactic background light (EBL)✤ This is not a comprehensive list of Fermi astrophysics

Note: All results in this talk are preliminary unless publishedFermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

2 /23

Fermi/LAT Collaboration
Stanford University & SLAC
NASA Goddard Space Flight Center
Naval Research Laboratory
University of California at Santa Cruz
Sonoma State University
University of Washington
Purdue Univeristy-Calumet
Ohio State University
University of DenverCommissariat a lʼEnergie Atomique, Saclay
CNRS/IN2P3 (CENBG-Bordeaux, LLR-Ecolepolytechnique, LPTA-Montpellier)
Hiroshima University
Institute of Space and Astronautical Science
Tokyo Institute of Technology
RIKEN
Instituto Nazionale di Fisica Nucleare
Agenzia Spaziale Italiana
Istituto di Astrofisica Spaziale e Fisica Cosmica
Royal Institute of Technology, Stockholm
Stockholms Universitet
Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

3 /23

Predecessor, EGRET✤ EGRET: 1991–2000❖ 271 gamma-ray sources (Hartman et al. 1999)• Only 38% (101 sources) have clear “identifications”
EGRET all-sky (galactic coordinates) E>100 MeV

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

4 /23

The First LAT Catalog (1FGL)✤ Fermi LAT 11 month data set (23.3 Ms livetime)❖ >1000 sources for TS = 2 Δlog(likelihood) > 25 (~4σ for 4 D.o.F.)❖ Typical 95% error radius is 10ʼ.

Absolute accuracy is better than 1ʼ
❖ Caveat: The Galactic ridge (|lat| < 1°, |lon| < 60°) has serious
difficulties: do not use them without detailed analysis
11 month

LAT all-sky, log scale, E>200 MeV (front), E>400 MeV (back)Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

5 /23

The First LAT AGN Catalog (1LAC)✤ 1079 TS>25 (~5σ), |b|>10° sources based on 11 month data set✤ 668 high-confidence (P>80%) associations with AGNs
❖ +186 lower-confidence (40%<P<80%) associations❖ 286 FSRQ
❖ 285 BL Lac (141 with measured z)❖ 69 unknown class❖ ~10 Radio galaxies

IN
IM

EL

PR

FSRQ
BLLac
Uncertain
Radio galaxies

RY
A

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

6 /23

The First LAT AGN Catalog (1LAC)✤ 1079 TS>25 (~5σ), |b|>10° sources based on 11 month data set✤ 668 high-confidence (P>80%) associations with AGNs
❖ +186 lower-confidence (40%<P<80%) associations❖ 286 FSRQ
❖ 285 BL Lac (141 with measured z)❖ 69 unknown class❖ ~10 Radio galaxies

IN
IM

EL

PR

FSRQ
BLLac
Uncertain
Radio galaxies

RY
A

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

6 /23

LAT Observations of TeV AGNs
✤ 21/28 TeV AGNs detected by Fermi-LAT (5.5 months), now 25/30❖ mostly BL Lacs, mostly HSPs
❖ 2 RGs: Centaurus A, M87❖ Most of the bright TeV blazars have been in low states since Fermi

launched

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

arXiv:0910.4881
7 /23

LAT Observations of TeV AGNs
✤ 21/28 TeV AGNs detected by Fermi-LAT (5.5 months), now 25/30❖ mostly BL Lacs, mostly HSPs
❖ 2 RGs: Centaurus A, M87❖ Most of the bright TeV blazars have been in low states since Fermi

launched

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

arXiv:0910.4881
7 /23

Multi-Wavelength Campaign✤ PKS 2155−304❖ First simultaneous GeV-TeV SED❖ Unexpected correlations in X-ray flux and GeV spectral index,

optical and TeV fluxes, and independent X-ray and TeV gamma-ray❖ Challenges for SSC (Synchrotron self-Compton) models✤ Mk 421❖ Most complete SED for Mk 421 to date

Mk 421

IN
IM

EL

PR
RY
A

PKS 2155−304
Aharonian, F. et al. 2009, ApJL, 696 L150

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

8 /23

TeV Emissions from LAT AGNs
✤ LAT count map above 30 GeV✤ VERITAS discovery of TeV source, VER J0521+21 (Atel 2260)❖ Most likely a radio-loud AGN, RGB J0521.8+2112

VERITAS (J. Holder @ Fermi symposium)
Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

9 /23

TeV Emissions from LAT AGNs
✤ LAT count map above 30 GeV✤ VERITAS discovery of TeV source, VER J0521+21 (Atel 2260)❖ Most likely a radio-loud AGN, RGB J0521.8+2112

VERITAS (J. Holder @ Fermi symposium)
Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

9 /23

SNR W44 Gamma-ray Image✤ Deconvolved image indicates shell-like gamma-ray emission✤ Maximum likelihood analysis prefer ring-like morphology rather

than disk-like morphology (> 8 σ)Middle-aged (~ 2.0×104 yr)
mixed-morphology SNR(radio: shell, thermal X-ray: centrally filled)
Distance: ~ 3 kpc
No. 3, 2006

SPITZER SURVEY OF SUPERNOVA REMNANTS

1487

Cloud-shell interactions
CO (Seta et al. 2004)
OH maser (Hoffman et al. 2005)
Green: Spitzer IRAC 4.5 μm
traces shocked HIIReach et al. (2006)
Fig. 8.—Spitzer IRAC color image of W44. The SNR appears ‘‘green’’ in the IRAC colors because channel 2 is relatively much brighter in the SNR shell than in
the surrounding ISM (including both the surrounding molecular cloud and the H ii regions to the east and northeast).

in channel 3. But channel 3 is mixed with the eastern H ii regionand other ISM emission outside the remnant. The remnant isbarely noticeable in IRAC channel 4 due to confusion with unrelated emission.
G36.6!0.7.—There is a possible shell of infrared emission
bounding the SNR toward the north, as well as a dark filament in
the north and clumps in the west and southwest. There is no clear
evidence for emission from shock fronts.
3C 396 (G39.2!0.3): Infrared emission is detected from thisremnant in three forms. First, faint, filamentary emission is detected in the western radio shell of this remnant, with IRAC colors
clearly distinct from normal interstellar emission. In Figure 9(left), the western shell appears green; a cut through the westernshell near ! ¼ 19h 03m 56:s3, " ¼ þ05$ 25 0 46 00 yields IRAC colors(<0.08)/0.2/0.69/1, suggesting emission from shocked, ionizedgas.
Second, there are two very bright infrared filaments, at! ¼ 19h 04m 18:s5, " ¼ þ05$ 20 0 33 00 and ! ¼ 19h 04m 17:s0, " ¼
þ05$ 27 0 07 00 (each %3000 long), just inside the eastern radio

shell. The filaments are clearly separated from the recently
detected pulsar wind nebula (Olbert et al. 2003) and are locatedwithin a region of exceptionally high radio polarization. We
suspect that these bright filaments, which are highly unusual,are part of the SNR, which is the only known structure in the interstellar medium at that location. The color ratios of the filamentsare (<0.05)/0.03/0.4/1, at a location at which the 8 #m surface
brightness is 30 MJy sr!1. These colors are similar to normalinterstellar medium, so the filaments could be photodissociation
regions (e.g., compressed filaments that were shocked long ago,rather than active shock fronts).
Finally, there is faint, diffuse emission surrounding the entireradio shell, with some bright, extended regions just outside theeastern periphery. The ‘‘blowout tail’’ discussed by Patnaik et al.
(1990) from radio data extends eastward from the remnant andwraps north then back over the top of the remnant. In the infrared, the ‘‘tail’’ starts with a bright region at ! ¼ 19h 04m 26:s0," ¼ þ05$ 27 0 55 00 that is connected to an intricate set of infrared
filaments that follow the radio structure, with the infrared region

Abdo et al. just appeared in Science Express on Jan/7th<http://www.sciencemag.org/cgi/content/abstract/science.1182787>
Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

10 /23

SNR W44 Gamma-ray Image✤ Deconvolved image indicates shell-like gamma-ray emission✤ Maximum likelihood analysis prefer ring-like morphology rather

than disk-like morphology (> 8 σ)1487

30:00.0

30:00.0

Green: Spitzer IRAC 4.5 μm
traces shocked HIIReach et al. (2006)
58:00.0

Spitzer IRAC 4.5 μm

SPITZER SURVEY OF SUPERNOVA REMNANTS

Cloud-shell interactions
CO (Seta et al. 2004)
OH maser (Hoffman et al. 2005)

2:00:00.0

No. 3, 2006

2:00:00.0

Middle-aged (~ 2.0×104 yr)
mixed-morphology SNR(radio: shell, thermal X-ray: centrally filled)
Distance: ~ 3 kpc

Preliminary

PSR B1853+01
18:56:00.0

54:00.0

58:00.0

18:56:00.0

Fig. 8.—Spitzer IRAC color image of W44. The SNR appears ‘‘green’’ in the IRAC colors because channel 2 is relatively much brighter in the SNR shell than in
the surrounding ISM (including both the surrounding molecular cloud and the H ii regions to the east and northeast).

in channel 3. But channel 3 is mixed with the eastern H ii regionand other ISM emission outside the remnant. The remnant isbarely noticeable in IRAC channel 4 due to confusion with unrelated emission.
G36.6!0.7.—There is a possible shell of infrared emission
bounding the SNR toward the north, as well as a dark filament in
the north and clumps in the west and southwest. There is no clear
evidence for emission from shock fronts.
3C 396 (G39.2!0.3): Infrared emission is detected from thisremnant in three forms. First, faint, filamentary emission is detected in the western radio shell of this remnant, with IRAC colors
clearly distinct from normal interstellar emission. In Figure 9(left), the western shell appears green; a cut through the westernshell near ! ¼ 19h 03m 56:s3, " ¼ þ05$ 25 0 46 00 yields IRAC colors(<0.08)/0.2/0.69/1, suggesting emission from shocked, ionizedgas.
Second, there are two very bright infrared filaments, at! ¼ 19h 04m 18:s5, " ¼ þ05$ 20 0 33 00 and ! ¼ 19h 04m 17:s0, " ¼
þ05$ 27 0 07 00 (each %3000 long), just inside the eastern radio

shell. The filaments are clearly separated from the recently
detected pulsar wind nebula (Olbert et al. 2003) and are locatedwithin a region of exceptionally high radio polarization. We
suspect that these bright filaments, which are highly unusual,are part of the SNR, which is the only known structure in the interstellar medium at that location. The color ratios of the filamentsare (<0.05)/0.03/0.4/1, at a location at which the 8 #m surface
brightness is 30 MJy sr!1. These colors are similar to normalinterstellar medium, so the filaments could be photodissociation
regions (e.g., compressed filaments that were shocked long ago,rather than active shock fronts).
Finally, there is faint, diffuse emission surrounding
the entire
2
radio shell, with some bright, extended regions just outside theeastern periphery. The ‘‘blowout tail’’ discussed by Patnaik et al.
(1990) from radio data extends eastward from the remnant andwraps north then back over the top of the remnant. In the infrared, the ‘‘tail’’ starts with a bright region at ! ¼ 19h 04m 26:s0," ¼ þ05$ 27 0 55 00 that is connected to an intricate set of infrared
filaments that follow the radio structure, with the infrared region

54:00.0

Deconvolved Image(2–10 GeV; front)

Abdo et al. just appeared in Science Express on Jan/7th<http://www.sciencemag.org/cgi/content/abstract/science.1182787>
0

200

400

600

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

800

1000
0
[counts/deg ]

200

400

600

800

1000

1200

1400

1600 1800[counts/deg 2 ]10 /23

SNR W44 Gamma-ray Image✤ Deconvolved image indicates shell-like gamma-ray emission✤ Maximum likelihood analysis prefer ring-like morphology rather

than disk-like morphology (> 8 σ)1487

30:00.0

30:00.0

Green: Spitzer IRAC 4.5 μm
traces shocked HIIReach et al. (2006)
58:00.0

Spitzer IRAC 4.5 μm

SPITZER SURVEY OF SUPERNOVA REMNANTS

Cloud-shell interactions
CO (Seta et al. 2004)
OH maser (Hoffman et al. 2005)

2:00:00.0

No. 3, 2006

2:00:00.0

Middle-aged (~ 2.0×104 yr)
mixed-morphology SNR(radio: shell, thermal X-ray: centrally filled)
Distance: ~ 3 kpc

Preliminary

PSR B1853+01
18:56:00.0

54:00.0

58:00.0

18:56:00.0

Fig. 8.—Spitzer IRAC color image of W44. The SNR appears ‘‘green’’ in the IRAC colors because channel 2 is relatively much brighter in the SNR shell than in
the surrounding ISM (including both the surrounding molecular cloud and the H ii regions to the east and northeast).

in channel 3. But channel 3 is mixed with the eastern H ii regionand other ISM emission outside the remnant. The remnant isbarely noticeable in IRAC channel 4 due to confusion with unrelated emission.
G36.6!0.7.—There is a possible shell of infrared emission
bounding the SNR toward the north, as well as a dark filament in
the north and clumps in the west and southwest. There is no clear
evidence for emission from shock fronts.
3C 396 (G39.2!0.3): Infrared emission is detected from thisremnant in three forms. First, faint, filamentary emission is detected in the western radio shell of this remnant, with IRAC colors
clearly distinct from normal interstellar emission. In Figure 9(left), the western shell appears green; a cut through the westernshell near ! ¼ 19h 03m 56:s3, " ¼ þ05$ 25 0 46 00 yields IRAC colors(<0.08)/0.2/0.69/1, suggesting emission from shocked, ionizedgas.
Second, there are two very bright infrared filaments, at! ¼ 19h 04m 18:s5, " ¼ þ05$ 20 0 33 00 and ! ¼ 19h 04m 17:s0, " ¼
þ05$ 27 0 07 00 (each %3000 long), just inside the eastern radio

shell. The filaments are clearly separated from the recently
detected pulsar wind nebula (Olbert et al. 2003) and are locatedwithin a region of exceptionally high radio polarization. We
suspect that these bright filaments, which are highly unusual,are part of the SNR, which is the only known structure in the interstellar medium at that location. The color ratios of the filamentsare (<0.05)/0.03/0.4/1, at a location at which the 8 #m surface
brightness is 30 MJy sr!1. These colors are similar to normalinterstellar medium, so the filaments could be photodissociation
regions (e.g., compressed filaments that were shocked long ago,rather than active shock fronts).
Finally, there is faint, diffuse emission surrounding
the entire
2
radio shell, with some bright, extended regions just outside theeastern periphery. The ‘‘blowout tail’’ discussed by Patnaik et al.
(1990) from radio data extends eastward from the remnant andwraps north then back over the top of the remnant. In the infrared, the ‘‘tail’’ starts with a bright region at ! ¼ 19h 04m 26:s0," ¼ þ05$ 27 0 55 00 that is connected to an intricate set of infrared
filaments that follow the radio structure, with the infrared region

54:00.0

Deconvolved Image(2–10 GeV; front)

Abdo et al. just appeared in Science Express on Jan/7th<http://www.sciencemag.org/cgi/content/abstract/science.1182787>
0

200

400

600

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

800

1000
0
[counts/deg ]

200

400

600

800

1000

1200

1400

1600 1800[counts/deg 2 ]10 /23

SNR W44 Gamma-ray Image✤ Deconvolved image indicates shell-like gamma-ray emission✤ Maximum likelihood analysis prefer ring-like morphology rather

than disk-like morphology (> 8 σ)1487

30:00.0

30:00.0

Green: Spitzer IRAC 4.5 μm
traces shocked HIIReach et al. (2006)
58:00.0

Spitzer IRAC 4.5 μm

SPITZER SURVEY OF SUPERNOVA REMNANTS

Cloud-shell interactions
CO (Seta et al. 2004)
OH maser (Hoffman et al. 2005)

2:00:00.0

No. 3, 2006

2:00:00.0

Middle-aged (~ 2.0×104 yr)
mixed-morphology SNR(radio: shell, thermal X-ray: centrally filled)
Distance: ~ 3 kpc

Preliminary

PSR B1853+01
18:56:00.0

54:00.0

58:00.0

18:56:00.0

Fig. 8.—Spitzer IRAC color image of W44. The SNR appears ‘‘green’’ in the IRAC colors because channel 2 is relatively much brighter in the SNR shell than in
the surrounding ISM (including both the surrounding molecular cloud and the H ii regions to the east and northeast).

in channel 3. But channel 3 is mixed with the eastern H ii regionand other ISM emission outside the remnant. The remnant isbarely noticeable in IRAC channel 4 due to confusion with unrelated emission.
G36.6!0.7.—There is a possible shell of infrared emission
bounding the SNR toward the north, as well as a dark filament in
the north and clumps in the west and southwest. There is no clear
evidence for emission from shock fronts.
3C 396 (G39.2!0.3): Infrared emission is detected from thisremnant in three forms. First, faint, filamentary emission is detected in the western radio shell of this remnant, with IRAC colors
clearly distinct from normal interstellar emission. In Figure 9(left), the western shell appears green; a cut through the westernshell near ! ¼ 19h 03m 56:s3, " ¼ þ05$ 25 0 46 00 yields IRAC colors(<0.08)/0.2/0.69/1, suggesting emission from shocked, ionizedgas.
Second, there are two very bright infrared filaments, at! ¼ 19h 04m 18:s5, " ¼ þ05$ 20 0 33 00 and ! ¼ 19h 04m 17:s0, " ¼
þ05$ 27 0 07 00 (each %3000 long), just inside the eastern radio

shell. The filaments are clearly separated from the recently
detected pulsar wind nebula (Olbert et al. 2003) and are locatedwithin a region of exceptionally high radio polarization. We
suspect that these bright filaments, which are highly unusual,are part of the SNR, which is the only known structure in the interstellar medium at that location. The color ratios of the filamentsare (<0.05)/0.03/0.4/1, at a location at which the 8 #m surface
brightness is 30 MJy sr!1. These colors are similar to normalinterstellar medium, so the filaments could be photodissociation
regions (e.g., compressed filaments that were shocked long ago,rather than active shock fronts).
Finally, there is faint, diffuse emission surrounding
the entire
2
radio shell, with some bright, extended regions just outside theeastern periphery. The ‘‘blowout tail’’ discussed by Patnaik et al.
(1990) from radio data extends eastward from the remnant andwraps north then back over the top of the remnant. In the infrared, the ‘‘tail’’ starts with a bright region at ! ¼ 19h 04m 26:s0," ¼ þ05$ 27 0 55 00 that is connected to an intricate set of infrared
filaments that follow the radio structure, with the infrared region

54:00.0

Deconvolved Image(2–10 GeV; front)

Abdo et al. just appeared in Science Express on Jan/7th<http://www.sciencemag.org/cgi/content/abstract/science.1182787>
0

200

400

600

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

800

1000
0
[counts/deg ]

200

400

600

800

1000

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1600 1800[counts/deg 2 ]10 /23

W44 Spectrum✤ Simple PL is rejected with 14σ✤ π0-decay dominant model is most natural explanation✤ Electron bremsstrahlung cannot completely be ruled out❖ Brems: amount of electrons should be comparable to protons❖ Inverse Compton: We ~ 1051 erg or quite intense photon field needed✤ Protons need to have a spectral break at ~ 10 GeV/c❖ Fast escape of high energy

particles with damping ofmagnetic turbulence dueto the dense environment(Ptuskin & Zirakashvili 2003)

Γ1 ~ 2Preliminary
WhippleΓ2 ~ 3

HEGRA
Milagro+ statistical error+ systematic error
Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

11 /23

SNR W51C and IC443✤ Middle-aged SNRs interacting with molecular clouds by LAT❖ W51C: age ~ 3×104 yr,

distance ~ 6 kpc, L = 1036 (D/6 kpc)2 erg s–1❖ IC443: age ~ (3~30)×104 yr, distance ~ 1.5 kpc✤ Spectral steepening similar to the W44 spectrum

π0-decay model can reasonably explain the data
❖ Leptonic scenarios have similar difficulties as W44❖

W51C

π0-decay dominant model
PR

IN

M

π0-decayIEL

π0-decay

IC443

Abdo et al.
(ApJ 706L 1A 2009)

RY
A

Bremsstrahlung
H.E.S.S.

proton spectral break~ 70 GeV/c

Inverse Compton

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

12 /23

Fermi Observations of Middle-Aged SNR✤ Common features of middle-aged SNRs observed by Fermi❖ Interacting with molecular clouds❖ Spectral steepening between GeV and TeV✤ SNRs observed by Fermi may give new clues on❖ Effect on cosmic ray accelerationfrom interacting molecular clouds✤ Ensemble of SNRs with different

cutoff may explain cosmic-ray
spectral index of ~2.7
❖ Shock acceleration @ ~2.0

Color: Fermi-LAT
Green contours: TeV (HESS) 4, 5, 6σ
Magenta contours: NANTEN
12CO(1–0) 0–10 km s–1
Cyan circle: radio boundary+: PSR J1809–2332

W28 Field

Preliminary

HESS J1801−233❖ Propagation effect is not sufficient

to describe the difference❖ Note: #(middle aged SNRs)>> #(young SNR)

A

B

C

HESS J1801−233
Smoothed Count Map(2–10 GeV)

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

12 /2313

Young SNR RX J1713.7-3946✤ TS map after subtraction of preliminary 1FGL catalog sources❖ Very complicated GeV emissions❖ North sources coincides with molecular clouds (CO and HII region)✤ Requires more statistics to distinguish hadronic or leptonic

nature of gamma-ray emissions
PR
IN

M

I
EL
RY
A

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

14 /23

SNR Cassiopeia A✤ Last SNR witnessed by human (AD 1680)✤ No apparent spectral break in LAT and MAGIC spectrum✤ Both leptonic and hadronic interpretation possible❖ Leptonic (Bremsstrahlung + IC)• B ~ 0.12 mG, We ~ 1x1049 erg❖ Hadronic (π0 decay)

to appear in ApJ• B > 0.12 mG, Wp ~ 5x1049 erg
PR

I=2.4, no break
I=2.1, Ebreak = 10 TeV

IN

M

I
EL
RY
A

IN
IM
RY
A

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

EL

IC

PR

Brems

15 /23

Common Features of LAT GRBs
GRB

# of
duration
events> 100 MeV

# ofevents
> 1 GeV

HighestLong-lived
Delayed
Extra
EnergyHE
Redshift
HE onset
component(arrival time)emission

080825C

long

~10

0

~0.6 GeV(~T0+28 s)

✔

✔

?

080916C

long

>100

>10

~13 GeV(~T0+17 s)

✔

✔

hint

081024B

short

~10

2

~3 GeV(~T0+0.6 s)

✔

✔

?

081215A

long

—

—

—

—

—

—

90217

long

~10

0

~1 GeV(~T0+15 s)

X

X

?

90323

long

~20

>0

—

—

✔

—

3.57

90328

long

~20

>0

—

—

✔

—

0.736

90510

short

>150

>20

~31 GeV(~T0+0.8 s)

✔

✔

✔

0.903

90626

long

~20

>0

—

—

✔

—

090902B

long

>200

>30

~33 GeV(~T0+82 s)

✔

✔

✔

1.822

90926A

long

>150

>50

~20 GeV(~T0+25 s)

✔

✔

✔

2.106

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

4.35

16 /23

Delayed HE Gamma-ray Emission✤ Opacity due to γγ → e+e− in the first peak?
❖ No evidence of spectral cut-off

0

GBM BGO0(260 keV-5 MeV)

400

d
20

15

e
40

0.26 – 5 MeV

60

0
80

100

1000

400
200
00

200

5
10
Time since trigger (s)

500

15

0

0

300

20

40

All LAT events

200

60

80

100

300
200
100
00

100

600
400
5
10
Time since trigger (s)

15

200

0

0
20

40

> 100 MeV

LAT(> 100 MeV)

5

60

80

100

10

15

5
0
0

5
10
Time since trigger (s)

10

15

5

0

Counts/sec

0Counts/bin

0

3

0

20

40

> 1 GeV

LAT(> 1 GeV)

2
1
0
-20

60

Counts/bin

20

80

100

1.5

6

1

4

0.5
00

5
10
Time since trigger (s)152Counts/sec

Counts/bin

20

Counts/bin

Counts/sec

0LAT(no selection)

Counts/bin

Counts/bin

20

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

1000

Counts/sec

20cCounts/bin

a b

2000
5
10
Time since trigger (s)

0.8

.7

00

54

500

3000

500

10

15

.8

1000

Counts/sec

1500

Counts/bin

3.6

8 – 250 keV

1000

0

Counts/bin

GRB 080916C

7.7

GBM NaI3 + NaI4
(8 keV-260 keV)

1500

0.0

Counts/bin✤ Late arrival of highest energy gamma rays
GRB 090926

0
0

20

40
Time since trigger (s)

60

80

100

Science 323 1688A (2009)13.2 GeV photon

17 /23

Delayed HE Gamma-ray Emission✤ Opacity due to γγ → e+e− in the first peak?
❖ No evidence of spectral cut-off

0

GBM BGO0(260 keV-5 MeV)

400

d
20

15

e
40

0.26 – 5 MeV

60

0
80

100

1000

400
200
00

200

5
10
Time since trigger (s)

500

15

0

0

300

20

40

All LAT events

200

60

80

100

300
200
100
00

100

600
400
5
10
Time since trigger (s)

15

200

0

0
20

40

> 100 MeV

LAT(> 100 MeV)

5

60

80

100

10

15

5
0
0

5
10
Time since trigger (s)

10

15

5

0

Counts/sec

0Counts/bin

0

3

0

20

40

> 1 GeV

LAT(> 1 GeV)

2
1
0
-20

60

Counts/bin

20

80

100

1.5

6

1

4

0.5
00

5
10
Time since trigger (s)152Counts/sec

Counts/bin

20

Counts/bin

Counts/sec

0LAT(no selection)

Counts/bin

Counts/bin

20

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

1000

Counts/sec

20cCounts/bin

a b

2000
5
10
Time since trigger (s)

0.8

.7

00

54

500

3000

500

10

15

.8

1000

Counts/sec

1500

Counts/bin

3.6

8 – 250 keV

1000

0

Counts/bin

GRB 080916C

7.7

GBM NaI3 + NaI4
(8 keV-260 keV)

1500

0.0

Counts/bin✤ Late arrival of highest energy gamma rays
GRB 090926

0
0

20

40
Time since trigger (s)

60

80

100

Science 323 1688A (2009)13.2 GeV photon

17 /23

GRB Long-Lived HE Emission✤ HE (>100 MeV) emission shows different temporal behavior❖ Temporal break in LE emission while no break in HE emission• Indication of cascades induced by ultra-relativistic ions?
• Angle-dependent scattering effects?
GRB 090510
GRB 080916C

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan18 /23Extra Component✤ Extra spectral component inconsistent with Band function❖ Both in low- and high-energy regions✤ This is a challenge to theoretical model❖ Low energy excess difficult to explain by inverse Compton❖ Early afterglow?
! F! (erg/cm2/s)

GRB 090902B
ApJ 706L 138A (2009)

GRB 090510

10"4
"5

10

"6

10

10"7

Time"integrated photon spectrum (0.5 s " 1.0 s)

"4

3

10

5

6

8

"5

! F! (erg/cm2/s)

10

"6

10

0.5 s " 0.6 s: Band (B fixed)
0.6 s " 0.8 s: Band + PL
"710

0.8 s " 0.9 s: Band
0.8 s " 0.9 s: Band (B fixed) + PL
0.9 s " 1.0 s: PL (LAT only)

10

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

102

3

10

104

5

10

6

10

107

8

10

Energy (keV)

19 /23Extragalactic Background Light✤ EBL is sensitive to star formation history, dust extinction, lightabsorption and re-emission by dust
❖ Direct measurements of the IR-UV EBL are very difficult because of

foreground subtraction✤ HE gamma rays are sensitive to EBL in IR to UV band

via γγ → e+e− process❖ EBL will steepen AGN/GRB spectra

above > 10 GeV

Hopkins et al. 2007, fesc=0.10
S&B Model ʻCʼ, f=0.02
Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

20 /23

Probing EBL with AGN and GRB✤ 10–100 GeV gamma rays can probe EBL in early universe✤ Requires many sources at various redshifts to untangle EBL

effect and intrinsic spectra❖ Fermi will have ~1000 of blazars and ~100 of GRBs with redshift✤ Distinguish competing models

τ(E,z) = 3
Model Predictions

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

21 /23

Constraining EBL Models✤ Test each model by null-hypothesis test
❖ Power-law x EBL absorption• Vary normalization for EBL absorption✤ An example with J0808-0751 with Steckerʼs baseline model❖ Consistent with normalization = 0 (no EBL)
❖ Inconsistent with normalization = 1 at 5.6σ significance• Steckerʼs baseline model excluded

RYA

2ln(L/L0)

IN
M

I
EL

Free opacity
normalization

PR

Opacity (τ)

J0808-0751 (z~1.8)

Energy (TeV)
Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

22 /23

Summary✤ Fermi LAT demonstrating very exciting science in an early stageof its operations❖ Already surpassing EGRET in many area

✤ Discovery of spectral steepening at a few GeV in several middle-

aged SNRs✤ Very different behaviors of GeV gamma-ray emissions from MeV
emissions from GRBs
✤ Gamma-ray emission > 10 GeV from AGN/GRB start constraining
EBL models✤ Data are now public❖ data access: http://fermi.gsfc.nasa.gov/ssc/data/access/❖ analysis tool: http://fermi.gsfc.nasa.gov/ssc/data/analysis/

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan23 /23

Summary✤ Fermi LAT demonstrating very exciting science in an early stageof its operations❖ Already surpassing EGRET in many area

✤ Discovery of spectral steepening at a few GeV in several middle-

aged SNRs✤ Very different behaviors of GeV gamma-ray emissions from MeV
emissions from GRBs
✤ Gamma-ray emission > 10 GeV from AGN/GRB start constraining
EBL models✤ Data are now public❖ data access: http://fermi.gsfc.nasa.gov/ssc/data/access/❖ analysis tool: http://fermi.gsfc.nasa.gov/ssc/data/analysis/

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan23 /23

BackupFermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan24 /23

Source Associations (3 Month List)+90

NumberOther blazar

2

Radio/X-ray pulsar

15

LAT γ-ray pulsar

14

HMXB

2

Globular cluster

1

LMC

1

Special cases

13

Unidentified

38

0

11

90

Radio galaxy

18

46

0

BL Lac

18

62

270

FSRQ

0

Class

!90
Unassociated
X!ray binary

AGN
Globular cluster

PulsarΘ95% ~0.14°(EGRET ~0.62°)>80% of sources have “associations”:
121 AGN class, 29 pulsars✤ Thanks to better angular resolution
better localization and S/B✤

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

25 /23

Source Associations (3 Month List)+90

Number30

Other blazar

2

Radio/X-ray pulsar

15

LAT γ-ray pulsar

14

HMXB

2

Globular cluster

1

LMC

1

Special cases

13

Unidentified

38

90

0

11

0

Radio galaxy

18

46

0

BL Lac

15
18

62

270

FSRQ

Galactic Latitude [deg]

Class

0
!15
!30
90

75

60

45

30

15
0
345 330
Galactic Longitude [deg]

315

300

285

270

!90
Unassociated
X!ray binary

AGN
Globular cluster

PulsarΘ95% ~0.14°(EGRET ~0.62°)>80% of sources have “associations”:
121 AGN class, 29 pulsars✤ Thanks to better angular resolution
better localization and S/B✤

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

25 /23

Cosmic Particle Accelerators✤ Origin of cosmic ray protons?
❖ Galactic SNRs (Supernova Remnants) are considered as the best

candidates for cosmic-rays below “Knee”• Only circumstantial evidence- Diffusive shock acceleration(Blanford&Eichler 1977)- CR energy sum consistent
with SNR kinetic energy(Ginzburg&Syrovatskii 1964)• No observational evidence
for hadronic acceleration• Spectral index (~2.7) is difficult to explain❖ Cosmic-rays above “Knee” areconsidered extragalactic• Gamma-ray bursts (GRB)• Active Galactic Nuclei (blazar)• Merging galaxy clusters
Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

26 /23

SNR/PWN Associations with LAT✤ Potential associations in LAT 3-month bright source list
0FGL Namel

J0617.4+2234 189.08b

Associations

3.07 SNR G189.1+3.0 (IC 443)

Age
Molecular(x103 y)clouds3~30✔

J1018.2-5858

284.30 -1.76 SNR G284.3-1.8 (MSH 10-53), PSR J1013-5915~10✔

J1196.4-6055

290.52 -0.60 SNR G290.1-0.8 (MSH 11-61A), PSR J1105-6107

10~20

✔

J1615.6-5049

332.35 -0.01 SNR G332.4+0.1 (MSH 16-51), PWN G332.5-0.28, PSR B1610-50~5?

J1648.1-4606

339.47 -0.71 PSR J1648-4611

J1714.7-3827

348.52?

✔

35~150✔

0.10 SNR G348.5+0.1 (CTB37A)

J1801.6-2327

6.54 -0.31 SNR G6.4-0.1 (W28)

J1814.3-1739

13.05 -0.09 PWN G12.82-0.02

J1834.4-0841

23.27 -0.22 SNR G23.3-0.3 (W41)

148?

✔

J1855.9+0126

34.72 -0.35 SNR G34.7-0.4 (W44)~20✔

J1911.0+0905

43.25 -0.18 SNR G43.3-0.2 (W49B)

1~4✔

J1923.0+1411

49.13 -0.40 SNR G49.2-0.7 (W51C)~20✔

J1954.4+2838

65.30

40~140X

0.38 SNR G65.1+0.6✤ It is very difficult to distinguish SNRs, PWNe and pulsars❖ Source confusions due to SNR/PWN/pulsar in close vicinity❖ One of useful tool is morphological identification
Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan27 /23

High-Energy Emissions from GRB (Past)✤ EGRET observations of delayed

Gonzalez, Nature 2003 424, 749

HE gamma-ray emissions❖ It is not straightforward to explain by

conventional electron synchrotron
models❖ Proton acceleration?
Origin of UHECR?

BATSE

EGRET/TASC

14 – 47s

47 – 80s

Hurley et al. 1994

Two γ >GeV @~T0

-18 – 14s

18 GeV γ @ ~T0+75 min

80 – 113s

113 – 211s
Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan28 /23

EGRET High-Energy GRB Spectra✤ 5 EGRET bursts with >50 MeV observations in 7 years❖ No evidence of cutoff or extra HE component in the summed

spectrum
Dingus et al. 1997

Composite spectrum of 5
EGRET Bursts

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

29 /23

Constraints on Bulk Lorentz Factor✤ Large luminosity and short variability time imply large opticaldepth due to γγ → e+e−
❖ Small emission region: R ~ cΔt❖ τγγ(E) ~ (11/180)σTN>1/E/4πR2• τγγ(1 GeV) ~ 7x1011 for fluence=106 erg/cm2, z=1, Δt=1 s✤ Relativistic motion (Γ ≫1) can reduce optical depth❖ Lager emission region: R ~ Γ2cΔt❖ Reduced # of target photons:

N>1/E ∝ Γ2β+2 (note: β ~ -2.2)• Blue shift of energy threshold:Eth ∝ Γ• Blue shift of spectrum:
N(E) = (ΓE)β+1❖ Overall reduction of optical depth:

Γ2β-2 ~ Γ-6.4

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

30 /23

Implications on Quantum Gravity
GRB 090510
Energy (MeV)✤ Lorentz invariance violation❖ Dispersion relation:

3

10(1 + z ! )nΩm (1 + z ! )3 + ΩΛ

dz !

102

✤ GRB 080916C (z=4.35)

50

5000
0
0

0.5

1

1.5

2

15000

100

10000

50

5000
0

Counts/bin

0.5

1

1.5

2

(d)

LAT
40 (All events)

4000

20

2000

Counts/bin

Counts/bin

0

AGN
GRB
(Biller 99) (Boggs 04)

0
(e)

LAT
4 (> 100 MeV)

400

2

200

0
3 LAT
(> 1 GeV)20(f) 20
10
5

1
0
-0.5

Counts/sec(c) 20000

Counts/sec

0
200 GBM BGOs
150 (0.26–5 MeV)Counts/sec

10000

0

MQG,1 > 3.0 x 1019 GeV/c2

GRB(Ellis 06/07)

15000

100

0

❖ Eh ~ 31 GeV @ Δt~0.86 s

Pulsar(Kaaret 99)(b)Counts/sec✤ GRB 090510 (z=0.903)

GBM NaIs
150 (8–260 keV)

0

0.5
1
1.5
Time since GBM trigger (263607781.97) (sec)AGN(Aharonian 08) GRB080916C

Energy [GeV]Counts/bin

MQG,1 > 1.3 x 1018 GeV/c2

3

-0.
0
Counts/bin❖ Eh ~ 13 GeV @ Δt~16.5 s

0.7

3

10

3
0.6
5

0

"

104

0.5

(1 + n) (Ehn − Eln )∆t =2H0 (MQG,n c2 )n

! z

(a)

2
1
2

Planck mass min M

QG

1016

1017

Fermi Observations of TeV Gamma-ray Sources
CTA Japan Workshop, JAN 9, 2010, ICRR. Japan

AGN(Albert 08)

1018

1019

(GeV)

GRB090510
31 /23